The present invention relates to grinding machines in general, and more particularly to grinding machines of the type wherein the workpieces to be treated are transported between the active surfaces of two rotary grinding wheels. Still more particularly, the invention relates to improvements in grinding machines of the type wherein the grinding wheels are movable toward each other in order to compensate for wear upon their active surfaces.
Grinding machines of the above outlined character are disclosed, for example, in Swiss Pat. No. 577,873. One of many purposes of such machines is to grind the ends of helical springs. The springs are transported sideways through the space between the parallel active surfaces of the grinding wheels so that each grinding wheel treats a different end of each spring which is located in the space between the active surfaces. The wear upon the active surfaces is quite pronounced; therefore, such machines are equipped with means for moving the grinding wheels sideways whenever the length of treated workpieces (as considered at right angles to the planes of the active surfaces) exceeds a predetermined value at the upper end of the range of acceptable lengths. In other words, the means for moving the grinding wheels must compensate for wear upon the active surfaces so that the length of treated workpieces invariably remains within the range of acceptable lengths. In presently known two-wheel grinding machines, the adjustments of grinding wheels are effected by hand. The person in charge must be conscientious, alert and experienced, especially since the wear upon both grinding wheels is not always identical and particularly if the person in charge must rely on visual observation of the width of space between the active surfaces and/or of the length of treated workpieces. In other words, the person in charge must ascertain, preferably without any delay or with negligible delay, that the length of treated workpieces is excessive and such person must also detect that grinding wheel which is to be shifted toward the other grinding wheel. Delays in detection of unsatisfactory workpieces and/or in appropriate adjustment of the grinding wheel or wheels result in substantial losses in output or customer complaints and attendant inconveniences.